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~74~2---------------------------------------------ARfiCLES------------------------~N~A~T~U~R~E~v~c~Jl~.. ~3~33~2='~·~'t~JN~E~t~9=88 Tolerance in T -cell-receptor transgenic mice involves deletion of nonmature CD4+8+ thymocytes Pawel Kisielow"t, Horst Bliithmann*, Uwe D. Staerz", Michael Steinmetz* & Harald von Boehmer" * Basel Institute for Immunology, CH-4005 Basel, Switzerland :j: Central Research Units, F. Hoffmann-La Roche & Co. Ltd, CH-4002 Basel, Switzerland The mechanism of self-tolerance is studied in T-cell-receptor transgenic mice expressing a receptor in many of their T cells for the male (H- Y) antigen in the context of class I H-2Db MHC antigens. Autospecific T cells are deleted in male mice. The deletion affects only transgene-expressing cells with a relatively high surface-density of CDS molecules, including nonmature CD4+CD8+ thymocytes, and is not caused by anti-idiotype cells. T LYMPHOCYTES recognize antigens on the surface of other products were absent from the pool of peripheral T cells and 12 14 cells in the context of molecules encoded by the major histocom­ medullary thymocytes - , but were present among cortical 1 12 13 patibility complex (MHC) by virtue of the heterodimeric T cell CD4+8+ thymocytes • . These results can be explained by receptor (TRC) which is composed of a and {3 polypeptide deletion of autospecific cells, but the alternative possibility that 2 3 chains • • In binding to its ligand, the a{3TCR is assisted by their absence is the result of a change of their phenotype caused 4 5 CD8 or CD4 accessory molecules • , which presumably interact by modulation or masking of surface molecules has not been with nonpolymorphic portions of class I or class II MHC excluded. 10 molecules respectivel/- • Mature T lymphocytes usually do The development of transgenic mice offers another approach not respond to self-MHC molecules presenting self-antigens. to analyse the mechanism of self-tolerance. To this end we have The question of whether the mechanism of immunological toler­ constructed transgenic mice expressing in a large fraction of ance involved deletion of autospecific lymphocytes has con­ their T cells an a{3TCR specific for a minor histocombatibility 1 cerned immunologists over decades \ but no direct evidence antigen (H-Y) present on male, but not female, cells. Fertilized for such a mechanism has been obtained, because the great eggs obtained from a cross of C57BL/6J x DBA/21 mice were diversity of receptors generated during lymphocyte development injected with genomic DNA harbouring the productively had made it impossible to follow individual clones of cells rearranged TCR a and {3 genes isolated from the B6.2.16 15 expressing receptors specific for self-antigens. cytolytic T-cell clone • This clone is specific for H-Y antigen Recently, two groups of investigators obtained monoclonal in the context of class I (H-2Db) MHC antigen and expresses antibodies (mAb) against the products of certain V{3 genes that a TCR {3-chain coded in part by the V{38.2 gene segment which 6 are expressed with unusually high frequency on T cells specific can be identified by the F23.1 antibodi . 12 14 for certain class II MHC-associated alloantigens - • Using The transgenic founder mouse 71 contained four copies of these antibodies, Kappler et al. and MacDonald et al. were able the a and two copies of the {3 transgenes integrated on the same 17 to show that in mice expressing the relevant class II MHC­ chromosome • It was crossed with C57L mice expressing H-2b associated antigens, cells expressing the particular V{3 gene MHC antigens, but lacking the V{38 gene family. Here we show that cells with the phenotype of the B6.2.16 clone that responded t Pennanent address: The Institute of Immunology and Experimental Therapy, Polish Academy to H-Y antigen were frequent in female but not in male trans­ of Sciences, Wroclaw, Poland. genic offspring, despite the fact that peripheral T cells in animals Table 1 Frequency of male (H-Y) antigen-specific precursors of proliferating T cells (PT-P) among CD4+8- and CD4-8+ T cells from normal and a/3TCR transgenic mice Donor of responding T cells af3TCR transgenic C57L Stimulation: female female male spleen cells CD4/CD8 (3000R) + IL-2 phenotype 1/frequency p* 1/frequency p !/frequency p C57BL/6 female CD4-8+ >25,000 >25,000 >25,000 C57BL/6 female CD4-8+ 2.3 (1.6-3.3) 0.66 1.8 (1.2-2.6) 0.87 2.3 (1.3-4.0) 0.18 +Con A CD4+8- NTt 6.4 (4.5-9.1) 0.60 NTt C57BL/6 male CD4-8+ 15,985 (5,029-50,802) 0.61 6.6 (4.8-9.0) 0.67 >25,000 CD4+8- NTt >25,000 NTt Lymph node cells were stained with a mixture of anti CD4-PE and anti-CD8-FITC mabs (see Fig. 1). CD4+8- and CD4-CD8+ T cells were separated on fluorescein activated cell sorter (FACS440, Becton Dickinson). Limiting numbers of CD4+8- CD4-8+ T cells (24 wells per group) were cultured for 8 days together with irradiated (3,000R) spleen cells (5 x 105 cells per cell) and interleukin-w (5% v/v) of partially purified 24 1 supernatant from Con A-stimulated rat spleen cells without or with Con A (2.5 f.Lg ml- ). Cells were collected after addition of eHJthymidine for the last 12 h of culture and incorporated radioactivity was measured by liquid scintillation counting. Negative control cultures contained no 25 responder cells. Frequencies were calculated as described elsewhere • * Probability, p, attached to the computed x2 (ref. 25). t NT, not tested. © 1988 Nature Publishing Group ~NA~TU~R=E~v~o=L~·~33~3~2~3~JU~N~E~t9~8~8------------------------ARTICL£S~-----------------------------------------7~43 17 of both sexes expressed both transgenes • T cells in male (but Littermates Lymph node cells not female) mice had an abnormal CD4/CD8 phenotype: over 90% of T cells in male transgenic mice were CD4-s-, or a expressed only low levels of CDS molecules, and the numbers of CD4+8-T cells were very small. The cellular composition of non transgenic male thymuses revealed that this unusual phenotype of male peripheral T cells was the consequence of deletion of auto­ specific thymocytes expressing high levels of CDS molecules, predominantly cortical CD4+8+ thymocytes. The deletion pro­ Q) c0 b cess spared cells expressing low levels of CDS molecules, but Q) UJ UJ 0 a.. a.. affected the precursors of single positive CD4+s- cells that were (/) transgenic !!' <t 0 ;;; not male-specific. This latter observation provides strong (\J 0 female ..2 evidence that double-positive CD4+8+ thymocytes contain pre­ u. y '0 ~ cursors of single positive CD4+s- and CD4-s+ T cells. ~ l'<l 0> 0 T cells in females ....J c Lymph nodes of female transgenic mice contained normal pro­ portions of CD4+8- and CD4-s+ T (Thy!+) cells which had transgenic normal levels of CD4 as well as CDS accessory molecules (Fig. male 1 a, b, d and e). But these differed in two respects from T cells in normal mice. Firstly, as previously described for~ transgenic 15 mice , most of them expressed the transgenic~ chain on their anti-Thy 1 ( FITC) anti-CD8 ( FITC) surface (Fig. 1 b). Secondly, as shown by limiting dilution analy­ Log green fluorescence sis of CD4-8+ T cells, one in six proliferated specifically in response to C57BL/ 6 male stimulator cells, as compared with Fig. 1 Comparison of cell surface expression of F23.1 + TCR f3 one in 16,000 in normal C57L female mice (see Table 1). As chain, CD4 and CDS molecules on lymph node T (Thy!+) cells only every second plated T cell responded to concanavalin A from female and male af3TCR transgenic mice and their nontrans­ (Con A), we conclude that at least 30% of CD4-s+ T cells in genic male littermate as analysed by two-colour flow cytometry. Lymph node cells were stained with biotinylated F23.1 monoclonal transgenic females have a phenotype similar to that of the antibody (mAb) followed by a mixture of fluorescein (FITC)­ B6.2.16 clone. CD4+8- T cells from transgenic mice did not labelled anti-Thy! mab with phycoerythrin-streptavidin (PEA) (a, show any male-specific proliferation, but did respond to Con band c) or with PE-conjugated anti-CD4 mAb followed by FITC A (Table 1). conjugated anti-CD8 mab ( d, e and fl. In panels a, b and c some Thy!- cells (B cells) stain nonspecifically with F23.1 mAb due to T cells in males the binding by Fe receptor. The presented data were obtained with As in transgenic females, lymph nodes of transgenic males one pair of 7-week-old af3TCR transgenic female and male litter­ contained normal proportions of Thyl + cells, and most of them mates. The same results were obtained with 3 other pairs of trans­ genic mice. expressed the transgenic ~ chain on their surface (Fig. lc). Methods. Single cell suspensions were prepared from lymph nodes Northern blot analysis of the a trans gene revealed comparable 17 (mesenteric, axillary, inguinal) and washed twice in RPM1-1640 levels of expression in T cells from female and male mice • and once in PBS with 5% FCS. For staining the following mAbs However, the CD4/CD8 phenotype ofT cells in male mice was were used: FITC-conjugated anti-Thy! (ref. 21), biotin-conjugated very different from that of females: 58% of Thy!+ cells were F23.1 (ref. 16), PE-conjugated anti-CD4 (anti-mouse L3T4, Becton CD4-s-, 35% were CD4-8+ but expressed low levels of CDS, Dickinson) FITC conjugated anti-CD8 (anti-mouse Lyt2, Becton and 7% were CD4+8- and expressed normal amounts of CD4 Dickinson).

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